Diversity of 16S rRNA genes of new Ehrlichia strains isolated from horses with clinical signs of Potomac horse fever.
Abstract: Ehrlichia risticii is the causative agent of Potomac horse fever. Variations among the major antigens of different local E. risticii strains have been detected previously. To further assess genetic variability in this species or species complex, the sequences of the 16S rRNA genes of several isolates obtained from sick horses diagnosed as having Potomac horse fever were determined. The sequences of six isolates obtained from Ohio and three isolates obtained from Kentucky were amplified by PCR. Three groups of sequences were identified. The sequences of five of the Ohio isolates were identical to the sequence of the type strain of E. risticii, the Illinois strain. The sequence of one Ohio isolate, isolate 081, was unique; this sequence differed in 10 nucleotides from the sequence of the type strain (level of similarity, 99.3%). The sequences of the three Kentucky isolates were identical to each other, but differed by five bases from the sequence of the type strain (level of similarity, 99.6%). The levels of sequence similarity of isolate 081, the Kentucky isolates, and the type strain to the next most closely related Ehrlichia sp., Ehrlichia sennetsu, were 99.3, 99.2, and 99.2%, respectively. On the basis of the distinct antigenic profiles and the levels of 16S rRNA sequence divergence, isolate 081 is as divergent from the type strain of E. risticii as E. sennetsu is. Therefore, we suggest that strain 081 and the Kentucky isolates may represent two new distinct Ehrlichia species.
Publication Date: 1995-04-01 PubMed ID: 7537065DOI: 10.1099/00207713-45-2-315Google Scholar: Lookup
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- Journal Article
- Research Support
- U.S. Gov't
- Non-P.H.S.
Summary
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This research study investigates new strains of Ehrlichia risticii bacteria found in horses diagnosed with Potomac horse fever, focusing on the genetic diversity present in the 16S rRNA genes. The results suggest that there may be two new, distinct species of Ehrlichia.
Understanding the Genetic Diversity of Ehrlichia risticii
- The aim of the research was to gauge the genetic divergence within the species or species complex of Ehrlichia risticii, the bacteria responsible for Potomac horse fever. This was done by determining the sequences of the 16S rRNA genes in several E. risticii isolates extracted from infected horses.
- A PCR (Polymerase Chain Reaction) technique was used to amplify the sequences of both six isolates from Ohio and three isolates from Kentucky. The sequences were then classified into three groups.
Identification of Sequence Variations
- Five of the isolates obtained from Ohio had sequences identical to the Illinois strain, which is the type strain of E. risticii.
- One isolate from Ohio, named isolate 081, had a unique sequence that diverged at 10 nucleotide positions from the type strain, demonstrating a similarity level of 99.3%.
- The sequences from the three Kentucky isolates were identical to each other, but had five base differences from the type strain, yielding a similarity level of 99.6%.
Comparative Similarities with Ehrlichia sennetsu
- The research compared the sequence similarities of the Ohio isolate 081, the Kentucky isolates, and the type strain with the closest relative species, Ehrlichia sennetsu. It found that the level of sequence similarity was 99.3%, 99.2%, and 99.2% respectively.
- This similarity level indicated that isolate 081 is as divergent from the type strain of E. risticii as the E. sennetsu species is.
Clinical Implications of the Study
- On the strength of their distinct antigenic profiles and the levels of 16S rRNA sequence divergence, the research posits that the isolate 081 and the Kentucky isolates could belong to two new distinct Ehrlichia species.
- These findings could have significant implications on how Potomac horse fever is diagnosed and treated in future, owing to the potential presence of two new species of the Ehrlichia bacteria.
Cite This Article
APA
Wen B, Rikihisa Y, Fuerst PA, Chaichanasiriwithaya W.
(1995).
Diversity of 16S rRNA genes of new Ehrlichia strains isolated from horses with clinical signs of Potomac horse fever.
Int J Syst Bacteriol, 45(2), 315-318.
https://doi.org/10.1099/00207713-45-2-315 Publication
Researcher Affiliations
- Department of Veterinary Biosciences, Ohio State University, Columbus 43210-1093.
MeSH Terms
- Animals
- Antigens, Bacterial
- Base Sequence
- DNA, Bacterial / genetics
- Ehrlichia / classification
- Ehrlichia / genetics
- Ehrlichia / isolation & purification
- Ehrlichiosis / microbiology
- Ehrlichiosis / veterinary
- Horse Diseases / microbiology
- Horses
- Molecular Sequence Data
- Phylogeny
- Polymerase Chain Reaction
- RNA, Bacterial / genetics
- RNA, Ribosomal, 16S / genetics
- Sequence Homology, Nucleic Acid
Citations
This article has been cited 16 times.- Budachetri K, Lin M, Yan Q, Chien RC, Hostnik LD, Haanen G, Leclère M, Waybright W, Baird JD, Arroyo LG, Rikihisa Y. Real-Time PCR Differential Detection of Neorickettsia findlayensis and N. risticii in Cases of Potomac Horse Fever.. J Clin Microbiol 2022 Jul 20;60(7):e0025022.
- Teymournejad O, Lin M, Bekebrede H, Kamr A, Toribio RE, Arroyo LG, Baird JD, Rikihisa Y. Isolation and Molecular Analysis of a Novel Neorickettsia Species That Causes Potomac Horse Fever.. mBio 2020 Feb 25;11(1).
- McKenzie HC, Funk RA, Trager L, Werre SR, Crisman M. Immunogenicity of Potomac horse fever vaccine when simultaneously co-administered with rabies vaccine in a multivalent vaccine or as two monovalent vaccines at separate sites.. Equine Vet J 2019 Nov;51(6):774-778.
- Xiong Q, Bekebrede H, Sharma P, Arroyo LG, Baird JD, Rikihisa Y. An Ecotype of Neorickettsia risticii Causing Potomac Horse Fever in Canada.. Appl Environ Microbiol 2016 Oct 1;82(19):6030-6.
- Gibson KE, Pastenkos G, Moesta S, Rikihisa Y. Neorickettsia risticii surface-exposed proteins: proteomics identification, recognition by naturally-infected horses, and strain variations.. Vet Res 2011 Jun 2;42(1):71.
- Rikihisa Y, Zhang C, Kanter M, Cheng Z, Ohashi N, Fukuda T. Analysis of p51, groESL, and the major antigen P51 in various species of Neorickettsia, an obligatory intracellular bacterium that infects trematodes and mammals.. J Clin Microbiol 2004 Aug;42(8):3823-6.
- Mott J, Muramatsu Y, Seaton E, Martin C, Reed S, Rikihisa Y. Molecular analysis of Neorickettsia risticii in adult aquatic insects in Pennsylvania, in horses infected by ingestion of insects, and isolated in cell culture.. J Clin Microbiol 2002 Feb;40(2):690-3.
- Kanter M, Mott J, Ohashi N, Fried B, Reed S, Lin YC, Rikihisa Y. Analysis of 16S rRNA and 51-kilodalton antigen gene and transmission in mice of Ehrlichia risticii in virgulate trematodes from Elimia livescens snails in Ohio.. J Clin Microbiol 2000 Sep;38(9):3349-58.
- Barlough JE, Reubel GH, Madigan JE, Vredevoe LK, Miller PE, Rikihisa Y. Detection of Ehrlichia risticii, the agent of Potomac horse fever, in freshwater stream snails (Pleuroceridae: Juga spp.) from northern California.. Appl Environ Microbiol 1998 Aug;64(8):2888-93.
- Reubel GH, Barlough JE, Madigan JE. Production and characterization of Ehrlichia risticii, the agent of Potomac horse fever, from snails (Pleuroceridae: Juga spp.) in aquarium culture and genetic comparison to equine strains.. J Clin Microbiol 1998 Jun;36(6):1501-11.
- Dutta SK, Vemulapalli R, Biswas B. Association of deficiency in antibody response to vaccine and heterogeneity of Ehrlichia risticii strains with Potomac horse fever vaccine failure in horses.. J Clin Microbiol 1998 Feb;36(2):506-12.
- Ohashi N, Zhi N, Zhang Y, Rikihisa Y. Immunodominant major outer membrane proteins of Ehrlichia chaffeensis are encoded by a polymorphic multigene family.. Infect Immun 1998 Jan;66(1):132-9.
- Zhi N, Rikihisa Y, Kim HY, Wormser GP, Horowitz HW. Comparison of major antigenic proteins of six strains of the human granulocytic ehrlichiosis agent by Western immunoblot analysis.. J Clin Microbiol 1997 Oct;35(10):2606-11.
- Mott J, Rikihisa Y, Zhang Y, Reed SM, Yu CY. Comparison of PCR and culture to the indirect fluorescent-antibody test for diagnosis of Potomac horse fever.. J Clin Microbiol 1997 Sep;35(9):2215-9.
- Wen B, Rikihisa Y, Mott JM, Greene R, Kim HY, Zhi N, Couto GC, Unver A, Bartsch R. Comparison of nested PCR with immunofluorescent-antibody assay for detection of Ehrlichia canis infection in dogs treated with doxycycline.. J Clin Microbiol 1997 Jul;35(7):1852-5.
- Engvall EO, Pettersson B, Persson M, Artursson K, Johansson KE. A 16S rRNA-based PCR assay for detection and identification of granulocytic Ehrlichia species in dogs, horses, and cattle.. J Clin Microbiol 1996 Sep;34(9):2170-4.
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